Transition from a fully ionized plasma to an absorbing surface

Almeida, N. A.; Benilov, M. S.; Franklin, R. N.; Naidis, G. V.

http://hdl.handle.net/10400.13/2593

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Abstract(s)

The ionization layer (presheath) separating a fully ionized low-temperature thermal plasma from the space-charge sheath adjacent to a solid surface is described by means of a (multi)ﬂuid model. The character of the solution is governed by α, the ratio of the ionization length to the mean free path for ion–atom collisions. If α 1, the solution is determined by physically transparent boundary conditions, namely, by the Bohm criterion at the sheath edge and the condition of full ionization on the plasma side of the ionization layer. If α<1, the latter condition becomes ineffective. An alternative boundary condition is found for a certain range of α below unity, αcr α<1. An approximate approach which spans the whole range of α is suggested. While being incomplete theoretically, this approach is sufﬁcient for practical purposes and gives results that are in agreement with experiment. On the other hand, the question of what is the lacking boundary condition in the range 0 <α<α cr remains open and challenging.

Keywords

Ionized plasma Absorbing surface Transition . Faculdade de Ciências Exatas e da Engenharia

URI

http://hdl.handle.net/10400.13/2593

Citation

Almeida, N. A., Benilov, M. S., Franklin, R. N., & Naidis, G. V. (2004). Transition from a fully ionized plasma to an absorbing surface. Journal of Physics D: Applied Physics, 37(22), 3107-3116.